25,979 research outputs found
Analytical stability and simulation response study for a coupled two-body system
An analytical stability study and a digital simulation response study of two connected rigid bodies are documented. Relative rotation of the bodies at the connection is allowed, thereby providing a model suitable for studying system stability and response during a soft-dock regime. Provisions are made of a docking port axes alignment torque and a despin torque capability for encountering spinning payloads. Although the stability analysis is based on linearized equations, the digital simulation is based on nonlinear models
Zero-shot keyword spotting for visual speech recognition in-the-wild
Visual keyword spotting (KWS) is the problem of estimating whether a text
query occurs in a given recording using only video information. This paper
focuses on visual KWS for words unseen during training, a real-world, practical
setting which so far has received no attention by the community. To this end,
we devise an end-to-end architecture comprising (a) a state-of-the-art visual
feature extractor based on spatiotemporal Residual Networks, (b) a
grapheme-to-phoneme model based on sequence-to-sequence neural networks, and
(c) a stack of recurrent neural networks which learn how to correlate visual
features with the keyword representation. Different to prior works on KWS,
which try to learn word representations merely from sequences of graphemes
(i.e. letters), we propose the use of a grapheme-to-phoneme encoder-decoder
model which learns how to map words to their pronunciation. We demonstrate that
our system obtains very promising visual-only KWS results on the challenging
LRS2 database, for keywords unseen during training. We also show that our
system outperforms a baseline which addresses KWS via automatic speech
recognition (ASR), while it drastically improves over other recently proposed
ASR-free KWS methods.Comment: Accepted at ECCV-201
Field-induced structure transformation in electrorheological solids
We have computed the local electric field in a body-centered tetragonal (BCT)
lattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to
examine the effects of a structure transformation on the local field strength.
For the ground state of an electrorheological solid of hard spheres, we
identified a novel structure transformation from the BCT to the face-centered
cubic (FCC) lattices by changing the uniaxial lattice constant c under the hard
sphere constraint. In contrast to the previous results, the local field
exhibits a non-monotonic transition from BCT to FCC. As c increases from the
BCT ground state, the local field initially decreases rapidly towards the
isotropic value at the body-centered cubic lattice, decreases further, reaching
a minimum value and increases, passing through the isotropic value again at an
intermediate lattice, reaches a maximum value and finally decreases to the FCC
value. An experimental realization of the structure transformation is
suggested. Moreover, the change in the local field can lead to a generalized
Clausius-Mossotti equation for the BCT lattices.Comment: Submitted to Phys. Rev.
Data-driven pedestrian re-identification based on hierarchical semantic representation
Limited number of labeled data of surveillance video causes the training of supervised model for pedestrian re-identification to be a difficult task. Besides, applications of pedestrian re-identification in pedestrian retrieving and criminal tracking are limited because of the lack of semantic representation. In this paper, a data-driven pedestrian re-identification model based on hierarchical semantic representation is proposed, extracting essential features with unsupervised deep learning model and enhancing the semantic representation of features with hierarchical mid-level ‘attributes’.
Firstly, CNNs, well-trained with the training process of CAEs, is used to extract features of horizontal blocks segmented from unlabeled pedestrian images. Then, these features are input into corresponding attribute classifiers to judge whether the pedestrian has the attributes. Lastly, with a table of ‘attributes-classes mapping relations’, final result can be calculated. Under the premise of improving the accuracy of attribute classifier, our qualitative results show its clear advantages over the CHUK02, VIPeR, and i-LIDS data set. Our proposed method is proved to effectively solve the problem of dependency on labeled data and lack of semantic expression, and it also significantly outperforms the state-of-the-art in terms of accuracy and semanteme
Consensus of self-driven agents with avoidance of collisions
In recent years, many efforts have been addressed on collision avoidance of
collectively moving agents. In this paper, we propose a modified version of the
Vicsek model with adaptive speed, which can guarantee the absence of
collisions. However, this strategy leads to an aggregated state with slowly
moving agents. We therefore further introduce a certain repulsion, which
results in both faster consensus and longer safe distance among agents, and
thus provides a powerful mechanism for collective motions in biological and
technological multi-agent systems.Comment: 8 figures, and 7 page
Maximized string order parameters in the valence bond solid states of quantum integer spin chains
We propose a set of maximized string order parameters to describe the hidden
topological order in the valence bond solid states of quantum integer spin-S
chains. These optimized string order parameters involve spin-twist angles
corresponding to rotations around or -axes, suggesting a
hidden symmetry. Our results also suggest that a local
triplet excitation in the valence bond solid states carries a
topological charge measured by these maximized string order parameters.Comment: 5 pages, 1 figur
Treatment of sanitary sewer overflow with fixed media bioreactors
Fixed media bioreactors (biofilters) are a promising and proven technology used for wastewater treatment in unsewered rural areas. As an on-site treatment system, it cart potentially provide high treatment efficiency with a relatively low cost and maintenance. This research expanded the application of fixed media bioreactors and tested their feasibility in the treatment of sanitary sewer overflows (SSO) at high hydraulic loading of 0.2 m/h. Sand, peat, and textile (felt) were used as media to treat simulated 6-h peak flows for a 25-year SSO event in the city of Columbus, Ohio. The influent SSO was a mixture of primary sludge from a wastewater treatment plant diluted with tap water. The efficiency of treatment was measured as changes in the concentrations of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solids (TSS). Sand as a filter medium had the best removal of organic matter with average 84% reduction of BOD5 and 90% of COD. The TSS removal was more than 90% in all media. Peat and felt were,somewhat more efficient than the sand in the TSS removal. The media type and influent BOD5 concentration were two major factors that impacted the treatment of BOD5 (p<0.007). For the treatment of COD, significant factors were media type, influent concentration, and time course of loading in each SSO event (ps <= 0.001)
Small ball probability, Inverse theorems, and applications
Let be a real random variable with mean zero and variance one and
be a multi-set in . The random sum
where are iid copies of
is of fundamental importance in probability and its applications.
We discuss the small ball problem, the aim of which is to estimate the
maximum probability that belongs to a ball with given small radius,
following the discovery made by Littlewood-Offord and Erdos almost 70 years
ago. We will mainly focus on recent developments that characterize the
structure of those sets where the small ball probability is relatively
large. Applications of these results include full solutions or significant
progresses of many open problems in different areas.Comment: 47 page
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